Affine Frequency Division Multiplexing for Communication and Channel Sounding: Requirements, Challenges, and Key Technologies

Channel models are crucial for theoretical analysis, performance evaluation, and deployment of wireless communication systems. Traditional channel sounding systems are insufficient for handling the dynamic changes of channels in the next-generation space–air–ground–sea integrated networks (SAGSIN), which often results in outdated channel models that fail to provide reliable prior information for communication systems. To address this challenge, this article proposes an integrated channel sounding and communication (ICSC) method as a practical solution. Unlike orthogonal frequency division multiplexing (OFDM), affine frequency division multiplexing (AFDM) provides a full delay-Doppler representation of the channel, achieving optimal diversity in time-frequency doubly dispersive channels and effectively addressing the aforementioned challenges. Thus, this article investigates the fundamental principles of AFDM, showing how it enables simultaneous communication and channel sounding, and explores key performance metrics for both functionalities. Additionally, the distinction and relationship between channel sounding, estimation, tracking, and scatterer sensing are clarified. Several potential application scenarios for AFDM-ICSC are also examined. Finally, the article highlights the key challenges in implementing AFDM-ICSC, outlines future research directions, and offers valuable insights for the continued development of this technology.